Flat wire conveyor belts have been in the market for many years. Flat wire conveyor belts are generally low maintenance and when positively driven with sprockets have little to no lateral shifting. With reference to FIG. 1, U.S. Pat. No. 2,619,306 discloses a flat wire conveyor belt 10 comprising a plurality of pickets 16, sometimes also referred to as wickets, and interconnecting rods 18 about which the pickets hinge. The rods 18 terminate on the side edges of the belt 10 in a small button head 19. The pickets 16 on belt 10 support the product to be conveyed and the rods 18 are utilized to hold the components of belt 10 together.
In a straight run, when a sprocket tooth is disposed within an opening defined by a link in the picket, the sprocket tooth relieves the tension in the adjacent pickets and concentrates it one location, thereby causing rod 18 to deflect at the sprocket tooth. This in turn causes the link in the picket which surrounds the sprocket tooth to become more highly loaded. Hence, fatigue and breakage may occur at one or more of the link areas surrounding a sprocket tooth where rod 18 meets picket 16.
Fatigue breakage at one or more of the picket areas of a flat wire conveyor belt is a function of the number of cycles that a particular area is flexed. This problem becomes even more pronounced as the conveyor belt becomes lighter in weight and more open due to efforts to reduce manufacturing costs and the resultant reduction in material usage.
A conveyor belt 100 as shown generally in FIG. 2 comprises a flat wire conveyor belt including a plurality of spaced tractive rods 180 disposed in succession and transversely with respect to a direction of travel T as represented by arrow T of belt 100, each rod 180 having two button head ends 182 and 184.
Belt 100 includes a plurality of rows of pickets 160 transversely disposed with respect to the direction of travel T, and interconnecting the succession of rods 180. Each row of pickets 160 is comprised of a plurality of links 105, each link connecting a rod 180 with a following rod in the succession.
Pickets 160 comprise a plurality of links 105; however, not all the links 105 within a single picket are identical. More particularly, in order to strengthen the outer edges of the conveyor belt, the edges of the picket are provided with links 110 having a first spacing or mesh size and the middle portion of the belt therebetween is provided with links 120 having a second spacing or mesh size. The exact number of links 110 or mesh openings on each end of the picket may vary depending upon the weight of the belt and other conditions. By way of example, picket 160 shown in FIG. 2 includes two links 110 defining four open mesh areas on each end of the picket for cooperation with a dual tooth sprocket. Hence, the pattern of openings in belt 100 provides both narrow openings for sprocket engagement and wider openings for product support that results in reduced material usage and belt weight, yet still provides sufficient strength for product support. Such a conveyor belt is know from U.S. Pat. No. 7,975,840, assigned to Cambridge International, Inc., the entire contents of which are hereby incorporated by reference.
The use of button head ends 182 and 184 on the rod 180, however, requires increased manufacturing costs and does not produce the desired finished appearance to the rod ends.
Accordingly, there exists a need in the marketplace for a flat wire conveyor belt having a lighter weight and reduced quantity of required material, while still retaining its strength so as to avoid fatigue failure, and which provides an aesthetically pleasing finished edge on the belt.